1. Field of the Invention
This invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming an elevated source/drain of a semiconductor device.
2. Description of the Prior Art
FIGS. 1A to 1C are sectional views for explaining a conventional method of forming an elevated source/drain of a semiconductor device.
Referring to FIG. 1A, an isolation layer 12 to isolate between devices is formed on a semiconductor substrate 11. A gate oxide layer 13 is formed on the semiconductor substrate 11 in which the isolation layer 12 is formed. A polysilicon layer for a gate and a mask insulation layer are sequentially formed on a resulting structure after forming the gate oxide layer 13. The mask insulation layer, the polysilicon layer and the gate oxide layer 13 are patterned, thereby forming a gate 14 having the mask insulation layer 15.
Referring to FIG. 1B, a spacer insulation layer is formed on a structure of FIG. 1A and spacer 16 is formed on a sidewall of the gate 14 and the mask insulation layer 15 by means of a dry etching method. A native oxide layer formed on a surface of the semiconductor substrate 11 is removed by means of a wet cleaning method. An epitaxial silicon layer 17 is selectively grown on the substrate 11 exposed by the spacer 16 by a chemical vapor deposition. An impurity ion is implanted into the epitaxial silicon layer 17 and an annealing process is performed. Hence, the impurity ion is activated and diffused into the substrate 11 so that an elevated source and a drain region 18 are formed, as shown in FIG. 1C.
In the mean time, the dry etching method utilizes the plasma. The surface of the substrate 11 is excessively exposed to the plasma so that loss of the substrate 11 is occurred and a crystal lattice thereof is destroyed by the plasma damage. It is problem in that the initial growth of the epitaxial silicon layer is difficult and a facet is generated during the initial growth, whereby doping profile of the elevated source and drains 18 is not uniformed.